Always on the right spot – overcoming optical focus issues in handheld Raman devices

Metrohm is pleased to present an Application Bulletin describing the benefits of Orbital-Raster-Scan (ORS), an optical sampling technology available with Metrohm’s handheld Raman system «Mira». As demonstrated in experiments, ORS sampling technology increases reproducibility of Raman signals from target active pharmaceutical ingredients (APIs), provides for fast results, and improves the matching power and consistency of known drug formulas to library spectra.

Handheld Raman spectrometers use a tightly focused laser beam to produce high spectral resolution. Due to the small size of the measuring spot, they are only able to capture a very small section of the sample. This can be a challenge when it comes to identifying heterogeneous formulations such as combinations of excipients or APIs. In this case, small particle size of each of the APIs and small spot size of the laser can make analysis of such formulations a time-consuming and difficult endeavour.

ORS sampling technology, on the other hand, «magnifies» the measuring spot, as the laser sweeps over an extended area of the surface taking measurements at several points and averaging them – a fast and yet very reliable solution to the challenge described. Results obtained from experiments on effervescent cold medicines containing three different APIs demonstrate that ORS-enhanced Raman spectroscopy provides for fast, accurate, and highly reproducible results, even when heterogeneous pharmaceutical formulations are analysed.